The present invention relates to automatic method and apparatus for stopping loom rotation at a constant crank angle, and more particularly related to an automatic system which constantly enables correctly compensates stoppage of loom rotation regardless unavoidable variation in actual stop angle due to inertia and/or other factors.
Loom rotation has to be often stopped in case of operation troubles such as faulty weft insertion and warp breakage. Stoppage of loom rotation at incorrect crank angles often disenables easy cloth-fell observation by operators and timed termination of sub-nozzle ejection. In order to avoid such troubles, it is in general employed in the field to predetermine an optimum stop crank angle for each operation trouble to be expected and to cease loom rotation at such a predetermined stop crank angle in case of the operation trouble. More specifically, a stop signal is generated at a predetermined moment in order to cancel power supply to the drive motor of the loom and initiate braking action on the loom rotation.
It is well known that a loom continues its rotation for a while before complete stop even after the braking action has been initiated. In addition, braking action in general deteriorates after long use due to abrasion and oil contamination, and/or variates from time to time depending on the environmental conditions. Even when initiation of braking action is well timed to generation of the stop signal, actual stop angle of loom rotation variates from time to time or changes in long use.
In order to avoid troubles to be caused by such variation or change in actual stop angle, it is generally employed at factories for operators to properly adjust the moment of stop signal generation on the basis of the actual stop angle every time the actual stop angle falls off the initially selected stop crank angle. Further, braking function in practice varies from loom to loom even when same type of looms are used in a factory. Therefore, even when a common stop crank angle is set for a number of loom, different looms in practice have different actual stop angles. This inter-loom variation in actual stop angle forces the operators to individually adjust the moment of stop signal generation, i.e. the moment of braking action initiation, from loom to loom in reference to the result of actual stop angle observation.